The establishment of an adequate air passageway is the first critical step in maintaining the ability of a seriously ill or injured patient to breathe, or in performing resuscitation on a patient unable to breathe. Endotracheal intubation (the placement of a tube through the nostrils or mouth and into the trachea itself) is the preferred method for establishing an air passageway when the trachea, nostrils and/or mouth are free of obstruction. When any such obstruction is present, however, endotracheal intubation is not possible, so that some other passageway for airflow must be established.
The most direct way to provide an air passageway under these circumstances is to form an ostomy or opening in the tracheal wall, and once formed, to keep the ostomy open by inserting a tracheal tube into it. Conventional tracheal tubes often include an open distal aperture and a circumferential inflatable cuff. The cuff provides a seal between the tracheal wall and the tracheal tube at a location cranial to the distal aperture. The seal so provided has several advantages, most importantly, that the seal prevents the intrusion blood, tissue or foreign matter into the lower trachea, bronchi and lungs, while permitting complete control and monitoring of the airflow established through the tracheal tube, including the provision of positive pressure ventilation. While the cuff is thin and flexible enough to provide a good seal, its thinness and flexibility make it easily subject to damage or puncture during introduction of the tracheal tube into the ostomy.
Several methods and devices are known for forming or enlarging an ostomy in a tracheal wall, and each are subject to their own advantages and drawbacks. For example, tracheostomy and cricothyrotomy procedures have been performed by using a scalpel to make an incision in the neck. Such procedures often entail a high degree of surgical skill to perform successfully, particularly since it is vital to locate and avoid unintentional severing of the blood vessels in'the area. These procedures can even require the surgeon to cut through several blood vessels and ligate (tie) them to the trachea, in order to achieve an adequately large ostomy. The length of time needed to perform these procedures (often, on the order of half an hour) is poorly suited to emergency treatment, when prompt restoration of the air passageway is critical. Moreover, the use of a scalpel to fully form an ostomy potentially causes undue trauma to the tissues surrounding the ostomy site, and can result in the formation of an unduly large or oversized opening in the soft tissue of the neck.
To minimize such trauma, it has been found desirable to initially incise only a small opening, and thereafter enlarge the opening with further dilation. For example, one prior technique for dilating an ostomy includes the use of a wire guide to facilitate the introduction of a dilator into the trachea. As disclosed in U.S. Pat. No. 4,677,978 (Melker, Jul. 7, 1987), such a technique involves the insertion of a needle and an over-the-needle catheter into the trachea. The needle is removed and the catheter replaced with a wire guide. A tapered, elongated, tubular dilator is positioned over the wire guide and introduced into the trachea. A drawback of this technique is that it requires the preliminary use of a scalpel to make an incision through the skin and cricothyroid membrane so that the needle can be inserted into the trachea. Even though intended to be performed in an emergency situation, the technique entails the sequential manipulation of several devices by the physician, which is time consuming and complicates the procedure.
The procedure disclosed in U.S. Pat. No. 4,889,112 (Schachner et al., Dec. 26, 1989) eliminates the use of the catheter and involves placing a wire guide through the needle itself. The ostomy formed by the needle is then dilated by the use of a device having a handle and a nose, the nose extending laterally from the axis of the handle. The nose has two jaws that spread apart for separating the tissue surrounding the ostomy, and the device is introduced into the trachea by positioning the elongated, tapered nose over the wire guide. While this type of device offers more powerful dilation than is possible with elongated tubular dilators, a problem with this device is that the unguarded nose must be inserted into the trachea with precision, and must be manipulated at an angle, in order to avoid perforating the posterior tracheal wall.
Another prior art technique for dilating an ostomy is the use of a tapered, elongated, tubular dilator or a series of telescopically positionable, tapered dilators with increasingly larger diameters. A problem with these dilators is that each dilator presents a pointed distal end to the posterior tracheal wall when introduced into the trachea. The risk of injury to the trachea is compounded by the toughness of the tracheal membrane, which resists the introduction of medical devices. Introducing these elongated dilators requires the application of considerable force. A physician must push the dilator into the trachea yet avoid puncturing the posterior tracheal wall.
The tracheal ostomy speculum of one of the inventors herein, disclosed in U.S. Pat. No. 5,217,007 (Ciaglia, Jun. 8, 1993), fully meets the problem of perforation of the posterior tracheal wall. The particularly disclosed speculum is not used with a wire guide, but instead includes a flexible and curved distal end on one of the members, and a cannula sized for extension through that end. The tip of the cannula is exposed and the cannula straightens the curved distal end during penetration of the tracheal wall. The cannula is retracted as penetration advances, however, so that only the flexible and curved distal end meets the posterior tracheal wall when the speculum is used to dilate the ostomy. Trauma to the posterior wall is thus avoided. While this speculum is admirably useful for its intended purpose, its use does require some degree of grip strength from the physician. Of course, the speculum provides no protection for the cuff on the tracheal tube to be inserted into the ostomy formed by the speculum. Moreover, it would be advantageous to reduce the cost or complexity of this or any other device for forming or dilating a tracheal ostomy.
It should therefore be clear that it would be highly desirable to find methods and devices for forming and dilating an ostomy in a tracheal wall which are atraumatic, that is, which avoid or substantially avoid the trauma and damage to the tracheal wall encountered in many prior methods and devices. It would also be highly desirable to find methods and devices which permit the enlargement of a formed ostomy without risk of perforating the rear of the trachea. It would further be desirable to find methods and devices which protect the cuff of a tracheal tube from damage during the insertion of the tracheal tube through the ostomy.